Multiple chamber airbags and methods

ABSTRACT

A two or more chambered airbag provides much improved safety and/or performance. A modified single chamber airbag can be used as the primary chamber of the two-chamber airbag. A piece of fabric of appropriate size is sewn to the inside or outside surface of the front panel of the primary chamber to create the secondary chamber. One or more apertures are opened between the primary and secondary chambers. In order for the secondary chamber to inflate properly, the tethers of the primary chamber are shortened to 50% to 80% of their original length. The size or location of the tether sewing to the inner surface of the front panel of the primary chamber is also adjusted to create a desired shape of the secondary chamber when deployed.

[0001] This application claims priority to and benefit of U.S.Provisional Patent Application Serial No. 60/216,545, filed Jul. 7,2000, and hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to a multi-chamber airbag or airbagcushion and method. Such a cushion may simultaneously exhibit a very lowamount of fabric utilized to produce the target airbag cushion incorrelation to an overall high amount of available inflation airspacewithin the cushion itself. These two correlative elements are combinedin what is defined as an effective fabric usage index (being thequotient of the amount of fabric utilized in the construction of theairbag cushion and the available inflation airspace volume). A cushionexhibiting low seam usage factor, low total fabric weight, low fabricusage factor and/or comprising two or more chambers is provided as wellas an overall vehicle restraint system including the inventive airbagcushion.

BACKGROUND OF INVENTION

[0003] All U.S. patents cited herein are hereby filly incorporated byreference.

[0004] Inflatable protective cushions used in passenger vehicles are acomponent of relatively complex passive restraint systems. The mainelements of these systems are: an impact sensing system, an ignitionsystem, a propellant material, an attachment device, a system enclosure,and an inflatable protective cushion. Upon sensing an impact, thepropellant is ignited causing an explosive release of gases filing thecushion to a deployed state which can absorb the impact of the forwardmovement of a body and dissipate its energy by means of rapid venting ofthe gas. The entire sequence of events occurs within about 100milliseconds. In the undeployed state, the cushion is stored in or nearthe steering column, the dashboard, in a door, or in the back of a frontseat placing the cushion in close proximity to the person or object itis to protect.

[0005] Inflatable cushion systems commonly referred to as air bagsystems have been used in the past to protect both the operator of thevehicle and passengers. Systems for the protection of the vehicleoperator have typically been mounted in the steering column of thevehicle and have utilized cushion constructions directly deployabletowards the driver. These driver-side cushions are typically of arelatively simple configuration in that they function over a fairlysmall well-defined area between the driver and the steering column. Onesuch configuration is disclosed in U.S. Pat. No. 5,533,755 to Nelsen etal., issued Jul. 9, 1996, the teachings of which are incorporated hereinby reference.

[0006] Inflatable cushions for use in the protection of passengersagainst frontal or side impacts must generally have a more complexconfiguration since the position of a vehicle passenger may not be welldefined and greater distance may exist between the passenger and thesurface of the vehicle against which that passenger might be thrown inthe event of a collision. Prior cushions for use in such environmentsare disclosed in U.S. Pat. No. 5,520,416 to Bishop, issued May 28, 1996;U.S. Pat. No. 5,454,594 to Krickl issued Oct. 3, 1995; U.S. Pat. No.5,423,273 to Hawthorn et al. issued Jun. 13, 1995; U.S. Pat. No.5,316,337 to Yamaji et al. issued May 31, 1994; U.S. Pat. No. 5,310,216to Wehner et al. issued May 10, 1994; U.S. Pat. No. 5,090,729 toWatanabe issued Feb. 25, 1992; U.S. Pat. No. 5,087,071 to Wallner et al.issued Feb. 11, 1992; U.S. Pat. No. 4,944,529 to Backhaus issued Jul.31, 1990; and U.S. Pat. No. 3,792,873 to Buchner et al. issued Feb. 19,1974, all of which are incorporated herein by reference.

[0007] The majority of commercially used restraint cushions are formedof woven fabric materials utilizing multifilament synthetic yarns ofmaterials such as polyester, nylon 6 or nylon 6,6 polymers.Representative fabrics for such use are disclosed in U.S. Pat. No.4,921,735 to Bloch issued May 1, 1990; U.S. Pat. No. 5,093,163 toKrummheuer et al. issued Mar. 3, 1992; U.S. Pat. No. 5,110,666 to Menzelet al. issued May 5, 1992; U.S. Pat. No. 5,236,775 to Swoboda et al.Aug. 17, 1993; U.S. Pat. No. 5,277,230 to Sollars, Jr. issued Jan. 11,1994; U.S. Pat. No. 5,356,680 to Krummheuer et al. Oct. 18, 1994; U.S.Pat. No. 5,477,890 to Krummheuer et al. issued Dec. 26, 1995; U.S. Pat.No. 5,508,073 to Krummheuer et al., issued Apr. 16, 1996; U.S. Pat. No.5,503,197 to Bower et al. issued Apr. 2, 1996 and U.S. Pat. No.5,704,402 to Bowen et al. issued Jan. 6, 1998, all of which areincorporated herein by reference.

[0008] As will be appreciated, the permeability of the cushion structureis an important factor in determining the rate of inflation andsubsequent rapid deflation following the impact event. In order tocontrol the overall permeability of the cushion, it may be desirable touse differing materials in different regions of the cushion. Thus, theuse of several fabric panels in construction of the cushion may prove tobe a useful design feature. The use of multiple fabric panels in thecushion structure also permits the development of relatively complexthree-dimensional geometries which may be of benefit in the formation ofcushions for passenger side applications wherein a full-bodied cushionis desired. While the use of multiple fabric panels provides severaladvantages in terms of permeability manipulation and geometric design,the use of multiple fabric panels for use in passenger side restraintcushions has historically required the assembly of panels havingdifferent geometries involving multiple curved seams.

[0009] As will be appreciated, an important consideration in cuttingpanel structures from a base material is the ability to maximize thenumber of panels which can be cut from a fixed area through close-packednesting of the panels. The term “seam” denotes any manner or method ofconnecting separate fabric panels or separate portions of a singlefabric panel. Thus, sewing (with thread, for example), welding (withultrasonic stitching, for example), or weaving panels or portionstogether (with a jacquard or dobby loom, for example), and the like, maybe employed for this purpose.

[0010] However, a problem still resides in the need for labor-intensivecutting and sewing operations for large-scale manufacture. Furthermore,since the costs of producing airbag fabrics are relatively high andthere is a general need to reduce such costs, there is a consequent needto more efficiently make use of the fabric by lowering the amount whichneeds to be cut (cutting operations also translate into higher laborcosts), reducing the amount of fabric used in order to providesubstantially lower packing volumes (in order to reduce the size of theairbag modules in cars since available space on dashboards, doors, andthe like, are at a premium within automobiles), and reducing theshipping weight of such products (which translates into lower shippingcosts), as well as other highly desired reasons. However, it has beenproblematic to reduce such utilized fabric amounts in the past withoutconsequently also reducing the available inflation airspace volumewithin the cushion product. There is a need then to reduce the amount oftime to produce airbag cushions while simultaneously providing thelowest amount of fabric and simultaneously allow for a sufficient volumeof air (gas) to inflate the target airbag cushion during an inflationevent (herein described as “available inflation airspace””). Such adesired method and product has not been available, particularly forpassenger-side airbags which, as noted previously require greater amountof fabric for larger volumes of air (gas) to provide the greatest amountof protection area to a passenger. With greater amounts of fabricneeded, generally this has translated into the need for longer seams toconnect and attach fabric panels, which in turn translates into greateramounts of time needed for sewing, and the like, operations.Furthermore, there is a need for simultaneously reducing the requiredamount of utilized fabric while providing sufficient volumes ofavailable inflation airspace within the target airbag cushion. Thus, aneed exists to produce an improved multi-chamber airbag cushion, andsuch a cushion having high available inflation airspace volume with aminimal requirement in fabric utilization to manufacture the overallcushion product.

[0011] U.S. Pat. No. 5,927,748 entitled Multi-Stage Inflatable Bag forVehicular Safety Systems describes a multi-stage airbag with an innersmaller bag and an outer larger bag construction. The inner bag isinflated using the full force of the inflator for the initial expansion.The outer bag is inflated through the inner bag, thus more slowly.However, the airbag described here is basically a bag-in-a-bagconstruction. It is more difficult to construct hence higher cost. Alsoit is difficult to put tethers in such bags to control the final shapeof the deployed bag. The vent is from the outer bag, thus the outer bagmay be too weak to protect a larger and heavier occupant.

[0012] U.S. Pat. No. 5,934,701 entitled Automobile Airbag describes anairbag that can provide protection against leftward and rightward aswell as frontal impacts. In one embodiment, an auxiliary chamber wasused. This auxiliary chamber was independently constructed with its ownfilling port.

[0013] U.S. Pat. No. 5,501,488 entitled Airbags with AlternateDeployment discloses a means to fabricate an airbag that, in addition toits normal reach, can deploy to a shorter reach when a driver is tooclose to the airbag at the moment of collision. In the normal mode ofdeployment normal vents are covered by released flaps, causing theairbag to exert a large rebound force on the driver following thedeployment. In the case where the driver is sitting just farther thanthe flap release position, the effect may be fatal.

[0014] WO Publication Number 003898A1 entitled An Airbag describes anairbag with multiple compartments connected by vents, which can beinflated sequentially. However, due to the complicated design, thefabrication cost will be high. Also, in order for the third chamber toinflate adequately, the pressure in the first chamber needs to be veryhigh. This could be very dangerous to a short occupant sitting close tothe airbag considering the fact that the excursion of the primarychamber is rather high, especially when the occupant is tilted sidewaysat the instant of collision.

SUMMARY OF THE INVENTION

[0015] In view of the foregoing, it is a general object of the presentinvention to provide a cost-effective, easy to manufacture airbagcushion for utilization within a vehicle restraint system. The term“vehicle restraint system” is intended to mean both inflatable occupantrestraining cushion and the mechanical and chemical components (such asthe inflation means, ignition means, propellant, and the like). It is amore particular object of the present invention to provide a vehiclerestraint system wherein the target airbag cushion has multiple chambersand preferably comprises very low amounts or weight of fabric. A furtherobject of this invention is to provide an easy-to-assemble airbagcushion which is minimally labor-intensive to manufacture, requires muchlower fabric costs due to a substantial reduction in the overallrequirement of utilized fabric amounts, and which also comprises anintegrated looped pocket for the disposition of an inflator can withinthe airbag cushion. It is still a further object of this invention toprovide a vehicle restraint system comprising an airbag cushion whichprovides a multiple chamber airbag with a large amount of availableinflation airspace volume simultaneously with a low length of seam (orseams) and low amount of utilized fabric necessary to manufacture thecushion. Another object of the invention is to provide a method ofmaking a low cost airbag cushion (due to low levels of labor required tosew the component parts together and reduced amount of fabric tomanufacture and cut) of simple and structurally efficient design.

[0016] To achieve these and other objects and in accordance with thepurpose of the invention, as embodied and broadly described herein, thepresent invention provides an airbag cushion having at least one fabriccomponent, and wherein said airbag cushion possesses an effective fabricusage factor of less than about 0.095. The effective fabric usage factoris derived from an effective fabric usage index which concerns (and isdefined as) the quotient of the total amount of fabric utilized tomanufacture the airbag cushion (measured in square meters) over thetotal volume of available inflation airspace within the airbag cushion(measured in liters). In order to exhibit a sufficiently low effectivefabric usage factor, the amount of fabric must be very low with acorrespondingly high available inflation airspace volume. Of course,this airspace volume will be the same for each factor since themeasurements of both factors (seam usage and fabric usage) are made forthe same bag. Such an airbag cushion may comprise at least two separatefabric panels or a single panel with portions which require connection.The inventive bag is able to provide high available inflation airspacevolumes due to the particular configurations of the used fabric panelsor portions. The preferred configurations permit more efficientutilization of fabric webs by cutting panels from the webs and producingless waste of unused fabric. The preferred embodiment is discussed ingreater detail below.

[0017] Although it is preferred that the airbag cushion be constructedof a fabric (hence the term fabric usage factor), it is to be understoodthat the airbag cushion may be formed of one or more fabrics or othermaterials such as films, laminates, etc. Consequently, the presentinvention encompasses the use of other airbag materials and can bedefined by an effective airbag material usage factor as well as aneffective fabric usage factor. The effective material usage factor isderived from an effective material usage index defined as the quotientof total amount of material utilized to manufacture the airbag cushion(measured in square meters) over the total volume of available inflationairspace within the airbag cushion (measured in liters).

[0018] The effective fabric usage factor (as defined within thecorrelating seam usage index formula, above) for the inventive airbagcushion is preferably less than about 0.095, more preferably less than0.09, still more preferably less than 0.085, even more preferably lessthan 0.08, and most preferably lower than 0.075. Thus, the volume ofavailable inflation airspace within the airbag cushion should be asgreat as possible with the amount of fabric utilized reduced to itsabsolute minimum while still providing sufficient protection to apassenger in an automobile during a collision event.

[0019] A driver-side airbag will generally comprise a low amount ofutilized fabric but also does not provide a correlative high volume ofavailable airspace; and the prior art passenger-side airbags requirelarge amount of fabric. Although the available inflation airspace volumein such conventional passenger-side airbags is rather large, the totalamount of utilized fabric is too large to meet the aforementionedpreferred effective fabric usage factor within that index. The inventivecushion therefore is relatively easy to manufacture, requires very lowsewing, or similar type attachment operations of its fabric panelcomponents, requires very low amounts of fabric, but is also configuredto provide an optimum large amount of available inflation airspace formaximum protection to a passenger during a collision event.

[0020] In at least one embodiment, the present invention also providesan airbag cushion possessing the required effective fabric usage factorwhich also comprises a looped pocket for introduction of the inflatorcan of an inflator assembly. The multi-chamber airbag need not becreated from mirror-image body panel sections as any configuration offabric panels will function properly in this invention as long as athree-dimensional inflatable cushion is formed during an inflation eventand a looped pocket is created in the airbag in which at least theinflator can of an inflator assembly is disposed.

[0021] Additional objects and advantages of the invention will be setforth in part in the description which follows, and in part will beobvious from the description, or may be learned by practice for theinvention. It is to be understood that both the foregoing generaldescription and the following detailed description of preferredembodiments are exemplary and explanatory only, and are not to be viewedas in any way restricting the scope of the invention as set forth in theclaims.

[0022] Current single-chamber airbags have two significant drawbacks:First, they may exert a large rebound force on the occupant afterdeployment, putting the occupant at risk of possible neck injury.Second, they may hurt rather than protect an occupant if the occupant issitting very close to the airbag (as shorter and/or older drivers oftendo) when a collision occurs. At least selected embodiments of themultiple-chamber or two-chamber airbag of the present inventiondescribed herein will reduce rebound dramatically and provide protectionfor an out of position occupant sitting close to the airbag.

[0023] At least one embodiment of the two-chamber airbag disclosedherein is based on the current single-chamber airbag design but withseveral novel modifications to provide much improved safety and/orperformance. The current single chamber airbag can be modified and usedas the primary chamber of the two-chamber airbag. In one embodiment, apiece of fabric of appropriate size is sewn to the outside surface ofthe front panel of the primary chamber to create the secondary chamber.One or more apertures are opened between the primary and secondarychambers. In order for the secondary chamber to inflate properly, thetethers of the primary chamber are preferably shortened to 50% to 80% oftheir original length. The size of the tether sewing to the innersurface of the front panel of the primary chamber is also adjusted tocreate a desired shape of the secondary chamber when deployed.

[0024]FIGS. 1 and 2 schematically compare the typical components used inthe manufacturing of a single chamber airbag (FIG. 1) and the new dualor multiple chamber airbag (FIG. 2). In FIG. 3, the step-wise sewingapproach for this new dual chamber airbag is illustrated. From FIG. 3,it is obvious that the manufacturing steps involved in the multi-chamberbag are similar to the current approach except for added steps forattaching the tether portions, attaching the smaller panel, addingventing between the chambers, etc.

[0025]FIGS. 4 and 5 compare schematically the design and the shapes ofthe single chamber airbag 10 and the two-chamber airbag 20 whendeployed.

[0026] The two-chamber airbag 20 shows significantly improved safetyperformance as compared to the single-chamber airbag 10 in terms ofreducing rebound and providing protection for an out of positionoccupant sitting very close to the airbag. Drop tests (where an 83-lb.weight was dropped on the inflated bags) showed that the rebounddistance of the weight from the two-chamber airbag was reduced as muchas 70% from that of the single chamber airbag. Impact tests (where themovement distance was measured from the weight initially resting in afixed position after it was impacted by the deploying airbag) showedthat the energy dissipated on the weight by the two-chamber airbag wasmuch less than that from the single-chamber airbag when the weight wasat the same initial rest position. In other words, the two-chamberairbag of the present invention dissipates the same amount of energy tothe occupant sitting much closer to the steering wheel, thus providingprotection for an out of position occupant sitting closer to the airbag.Inflation tests showed that due to the shortened tether, the primarychamber of the two-chamber airbag inflated much faster with a muchshorter maximum excursion length than the single chamber airbag, againproviding protection for an out of position occupant sitting close tothe airbag.

BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings, which are incorporated in andconstitute a part of this specification, illustrate several potentiallypreferred embodiments of the invention and together with the descriptionserve to explain the principles of the invention wherein:

[0028]FIG. 1 is a schematic perspective view of the components of asingle chamber tethered airbag.

[0029]FIG. 2 is a schematic perspective view of the components of oneembodiment of the multiple chamber airbag of the present invention.

[0030]FIG. 3 is a schematic perspective view of the assembly steps ofthe airbag of FIG. 2.

[0031]FIG. 4 is a schematic cross-section representation of an inflatedtethered single chamber airbag.

[0032]FIG. 5 is a schematic cross-section illustration of an inflateddual chamber airbag of the present invention such as that of FIG. 2.

[0033]FIGS. 6 and 7 are exemplary fabric layout diagrams.

[0034]FIGS. 8 and 9 are exemplary cross section illustrations ofrespective inflated two-chamber airbag embodiments of the presentinvention.

[0035]FIG. 10 is a part diagram of a tether of the present inventionwith vent openings.

[0036]FIG. 11A is a schematic side view diagram of a rebound test.

[0037]FIG. 11B is a graphical representation of rebound distance data.

[0038]FIG. 12A is a schematic side view representation of an impacttest.

[0039]FIG. 12B is a graphical representation of impact test data.

[0040]FIGS. 13 and 14 are respective cross section illustrations ofinflated two-chamber airbag embodiments of the present invention havingtethered secondary chambers.

[0041]FIG. 15 is a cross section representation of an inflatedthree-chamber airbag in accordance with another embodiment of thepresent invention.

[0042]FIG. 16 is a schematic representation of an inflated conventionalbag-in-bag passenger airbag.

[0043]FIGS. 17 and 18 are schematic respective cross section views ofinflated two-chamber passenger airbag embodiments in accordance with thepresent invention.

[0044]FIG. 19 is a front view illustration of a two-chamber passengerairbag of the present invention.

[0045]FIG. 20 is a cross section representation of the airbag of FIG.19.

[0046]FIGS. 21 through 23 are respective side view illustrations ofstages of deployment of two-chamber passenger airbag embodiments of theinvention. FIGS. 21A-23A are directed to an embodiment with a smallsecondary chamber. FIGS. 21B-23B are directed to an embodiment with alarger secondary chamber.

[0047]FIGS. 24 through 26 are schematic side view representations of thestages of deployment of yet another passenger airbag embodiment of thepresent invention.

[0048]FIGS. 27 and 28 are respective cross section illustrations ofpassenger airbag embodiments of the present invention including aninternal baffle or tether in the secondary chamber.

[0049]FIG. 29 is a schematic assembly drawing and cross section view ofa single chamber tethered airbag.

[0050]FIGS. 30 and 31 are respective assembly drawings and cross sectionviews of two chamber airbag embodiments in accordance with the presentinvention.

[0051]FIGS. 32 through 36 are respective fabric layout diagrams.

[0052]FIG. 33 shows a tethered single chamber airbag layout.

[0053]FIGS. 32 and 34 through 36 show multiple chamber airbag layouts.

[0054]FIG. 37 is a schematic representation of the production of amultiple chamber airbag of the present invention.

[0055]FIG. 38 is a schematic representation of the assembly and crosssection of a three chamber airbag of the present invention.

[0056]FIGS. 39 through 41 are respective fabric layout diagrams.

[0057]FIG. 39 is a fabric layout diagram of a single chamber tetheredairbag.

[0058]FIGS. 40 and 41 are fabric layout diagrams of multiple chamberedairbag of the present invention.

[0059]FIG. 42 is a schematic cross section view of a three chamberpassenger airbag of the present invention.

[0060]FIG. 43 is an aerial view of a portion of a fabric web with linesindicating the specific locations for cutting to form six separatemultiple chamber passenger airbag cushions.

[0061]FIG. 44 is an aerial view of a portion of a fabric web with linesindicating the specific preferred locations for cutting to form two setsof fabric panels to manufacture two separate inventive multiple chambertop mount airbag cushions, each for the inclusion within a vehiclerestraint system configured within a module.

DETAILED DESCRIPTION OF THE INVENTION

[0062] Reference will now be made in detail to potentially preferredembodiments of the invention, examples of which have been illustrated inthe accompanying drawings. It is to be understood that it is in no wayintended to limit the invention to such illustrated and describedembodiments. On the contrary, it is intended to cover all alternatives,modifications and equivalents as may be included within the true spiritand scope of the invention as defined by the appended claims andequivalents thereto.

[0063] The current single-chamber airbag (FIGS. 1 and 4) has twosignificant drawbacks: First, it may exert a large rebound force on theoccupant after it is deployed, putting the occupant at possible risk ofneck injury. Second, it may hurt rather than protect an occupant if theoccupant is sitting very close to the airbag (as shorter and/or olderdrivers often do) when a collision occurs. The two-chamber (or threechamber) airbag of the present invention can reduce the rebounddramatically and can provide protection for an out of position occupantsitting close to the airbag.

[0064] At least one embodiment of the two-chamber airbag disclosedherein is based on the current single-chamber airbag design but withseveral novel modifications to provide much improved safety andperformance (FIGS. 2, 3, and 5). The current single chamber airbag canbe modified to be used as the primary chamber of the two-chamber airbag.A piece of fabric 22 of appropriate size is sewn to the outside (orinside) surface of the front panel 24 of the primary chamber to createthe secondary chamber. One or more apertures 26 are opened between theprimary and secondary chambers. In order for the secondary chamber toinflate properly, the tethers 28 of the primary chamber are preferablyshortened to 50% to 80% of their original length. The size of the tethersewing to the inner surface of the front panel of the primary chamber isalso adjusted to create a desired shape of the secondary chamber whendeployed. Rear panel 30 of the primary chamber includes vent openings 32and a gas inlet.

[0065]FIGS. 1 and 2 schematically compare the typical components used inthe manufacturing of a current single chamber airbag 10 and the new dualchamber airbag 20 (FIGS. 4 and 5). In FIG. 3, the step-wise sewingapproach for this new dual chamber airbag 20 is illustrated. From FIG.3, it is obvious that the manufacturing steps involved in the multiplechamber bag 20 of the present invention is similar to the currentapproach except for the added steps of attaching the tether portions,attaching the smaller panel, adding vents between the primary andsecondary chambers, etc.

[0066]FIGS. 4 and 5 of the drawings compare schematically the design andthe shapes of the single chamber airbag 10 and the two-chamber airbag 20when deployed.

[0067] The two-chamber airbag 20 preferably shows significantly improvedsafety performance as compared to the single-chamber airbag in terms ofreducing rebound and providing protection for an out of positionoccupant sitting very close to the airbag. Drop tests (where an 83-lb.weight was dropped on the inflated bags) showed that the rebounddistance of the weight from the two-chamber airbag was reduced as muchas 70% from that of the single chamber airbag (FIG. 11). Impact tests(where the movement distance was measured from the weight initiallyresting in a fixed position after it was impacted by the deployingairbag) showed that the energy dissipated on the weight by thetwo-chamber airbag was much less than that from the single-chamberairbag when the weight was at the same initial rest position (FIG. 12).In other words, the two-chamber airbag dissipates the same amount ofenergy to the occupant sitting much closer to the steering wheel, thusproviding protection for an out of position occupant (OOPO) sittingclose to the airbag. The inflation test showed that due to the shortenedtether, the primary chamber of the two-chamber airbag inflated muchfaster with a much shorter maximum excursion length than the singlechamber airbag, again providing protection for an out of positionoccupant sitting close to the airbag.

[0068] Selected Objects of at Least Some of the Embodiments of thePresent Invention

[0069] 1. To provide a new and improved airbag for avoiding or reducinginjuries caused by the airbag itself during deployment.

[0070] 2. To provide a new and improved airbag that can provideprotection for an out of position occupant sitting close to the airbagat the instant of collision.

[0071] 3. To provide a new and improved airbag that is simple and easyto construct thus reducing the production cost. Selected Advantages ofat Least One Embodiment of the Present Invention

[0072] 1. Low cost and easy to construct: The two-chamber airbag is verymanufacturing friendly. Most plants can produce such bags without anynew equipment. The only extra cost is the piece of fabric that definesthe outer surface of the secondary chamber.

[0073] 2. Tethered Design: The two-chamber airbag is tethered, it isvery easy to control the shape and excursion of the deployed bag bycontrolling the length and position of the tether.

[0074] 3. Stronger secondary chamber: In the two chamber airbag design,the final vent of the secondary chamber is through the primary chamber,thus having a relatively strong secondary chamber.

[0075] 4. High safety performance: The two-chamber airbag provides asofter landing for the occupant. It significantly reduces the rebound,minimizing the injuries caused by the deploying airbag. It also providesprotection for the short occupant sitting close to the airbag.

[0076] The secondary chamber may have other shapes, e.g. 3D. Thesecondary chamber may also be tethered. The fabric used for thesecondary chamber may be softer than that for the primary chamber. Thisconcept can also be applied to passenger side bags.

[0077] Uniqueness and Advantages of Multiple Chamber Airbags

[0078] 1. Low Cost and Easy to Construct

[0079] As compared to the airbags of others, one advantage is simpleconstruction and low cost. The two-chamber airbag is a uniquemodification of current production airbags. It is very manufacturingfriendly. The plant can produce such bags without adding new equipment.The only extra cost is the piece of fabric that defines the outer (orinner) surface of the secondary chamber. However, by novel fabriccutting design, the new airbag actually uses less fabric than thecurrent production bag (see, for example, FIGS. 6 and 7). There is lesswasted fabric per yard of starting material.

[0080] 2. Tethered Design

[0081] The two-chamber airbag is tethered, hence it is very easy tocontrol the shape and excursion of the deployed bag by controlling thelength and position of the tether. This is quite different from most ofthe airbags that are not tethered. For example, by shortening the tetherlength, a desired shape is formed that can actually act as a catcher forthe out-of-position occupant (see FIGS. 8 and 9 for both outside andinside sewn secondary chamber).

[0082] Further, when the tethers are attached in such a way that thesewn portion of the tether and front fabric of the primary chamber (inthe case of outside sew) or the secondary chamber fabric (in the case ofinside sew) form a closed chamber, this chamber can act as a modulatorto further control the inflation rate of the secondary chamber. In thiscase, the interconnecting vents are opened inside the sewing diameter.FIG. 10 shows one means on how to control the inflation rate as anexample. Holes of appropriate size are opened on the sewn tether atlocations such that they partially overlap the interconnecting vents. Atleast one slit may be cut on the holes so that the holes will enlarge athigh pressure.

[0083] The function of the thus formed “gas regulator” is as follows: Itrestricts the flow of the gas at initial stages such that the inflationof the secondary chamber is further delayed to protect the out ofposition occupant who sits very close to the airbag. When the primarychamber pressure is built up, the slit will open to allow gas flow intosecondary chamber quickly to protect normal positioned heavier occupant.This feature is particularly effective when a two-stage inflator is used(FIGS. 8-10).

[0084] 3. Stronger Secondary Chamber

[0085] In at least one of the present designs, the size of the secondarychamber is smaller than the primary chamber. Also the final vent of thesecondary chamber is through the primary chamber. This design enables arelatively strong secondary chamber when fully inflated for protectionof a heavier occupant.

[0086] 4. High Safety Performance

[0087] The two-chamber airbag can provide a softer landing for theoccupant. It can significantly reduce the rebound, minimizing anyinjuries caused by the deploying airbag itself. It also providesprotection for the short occupant sitting close to the airbag.

[0088] Following are Test Results:

[0089] The inflation test (cold gas test, not actual inflator) showedthat the primary chamber of the two-chamber airbag reached maximumpressure much faster than the control bag (single chamber productionbag) (38 ms vs. 54 ms). The typical airbag inflation time in anautomobile using an actual inflation (hot gas inflation) is about 33 msfor a driver bag and about 52 ms for a passenger bag. At this stage, thesecondary chamber was only partially inflated. The maximum excursion ofthe primary chamber of the two-chamber bag was also much shorter thanthe control bag at this stage due to shortened tethers. This is verybeneficial to a shorter driver sitting very close to the steering wheel.

[0090] The drop test where a weight (of 83 lbs.) is dropped over theinflated airbag showed that the two-chamber airbag had significantlyshorter rebound distance than the control bag. This will significantlyreduce the injuries caused by bouncing back effects. FIG. 11 comparesthe rebound distance of the control bag and three two-chamber bags withdifferent tether sewing diameters and tether lengths.

[0091] Drop tests were conducted by dropping a weight of 83 lbs. from aheight of 6 feet onto the inflated bag. The 12 inch×24 inch surface ofthe weight facing the bag was in the horizontal plane and the weight wasconstrained so it could move only up or down in the vertical direction.The peak deceleration rate as well as the peak-rebound height of theweight was recorded.

[0092] The data show that when the tether length is substantiallyshortened, the rebound distance is reduced by as much as 70%. At thesame time, the peak deceleration, which is a measure of the forceexperienced by the occupant, is also reduced for the two-chamber airbagby approximately 10%.

[0093] Impact tests were conducted in the same facility but with theweight being suspended on a flexile tether a fixed distance above thebag. The bag was inflated into the suspended weight. The maximum heightthe weight reached on impact was recorded.

[0094] The impact test showed that the two-chamber airbag had much lessimpact force on the object rested at a fixed position as measured by theobject movement. FIG. 12 compares the movement of the control bag andthree two-chamber bags with different tether sewing diameters and tetherlengths.

[0095] The height change of the object after it is impacted by thedeploying airbag is an indication of the energy dissipated on the bodyby the inflating bag. FIG. 12 clearly shows that the energy dissipatedon the body by the two-chamber airbags is much less than that by thecontrol bag when the object rests at the same initial position. Forexample, when the object initially rests at 10 inch from the base of theairbag, after it is impacted by the inflating airbag, it moves more than20 inches by the control bag. In contrast, it only moves less than 4inches by the two-chamber airbag with 160 mm tether length. Thisprovides evidence of enhanced protection of an out-of-position occupantsitting very close to the multiple chamber airbag during airbagdeployment.

[0096] Multiple Chamber Airbag Dimensional Parameters

[0097] The volume of the current single chamber production driver airbagis about 53-60 liters. The secondary chamber volume of the new bag isabout 12 liters and the primary chamber volume of the new bag is about38 liters. The tether length of the current single chamber productiondriver bag is approximately 300 mm. The tether length of the primarychamber of new bag can be 160-180 mm.

Variations

[0098] Secondary chambers can also be tethered, as illustrated in FIGS.13 and 14.

[0099] Multi-Chamber Airbag

[0100] The concept can be easily applied to three or more chamber bags.FIG. 15 shows one example of a three-chamber airbag of the presentinvention produced by adding an intermediate chamber in between theprimary and secondary chambers. The function of the intermediate chamberis to further modulate the gas flow characteristics to achieve desiredperformance.

[0101] Preferably, the airbags disclosed herein consume less fabric thanany prior airbags as a result of novel fabric cutting schemes as shownin FIGS. 32 and 34-36.

[0102] In addition to the fabric savings mentioned shown in the above,further improvement can be realized by using octagon shaped primarychambers as shown in FIGS. 34 and 36.

[0103] In addition to the primary chamber, the secondary chamber canalso use a polygon shaped panel or pleats could be formed to create athree dimensional secondary panel as shown in FIG. 36.

[0104] The proposed multiple chamber bag is manufacture friendly and theproposed production process is shown in FIG. 37.

[0105] In addition to the secondary chamber, a third chamber can beadded as shown in FIGS. 37 and 38 to further delay the inflation of theairbag closer to the occupant.

[0106] Addition of the third chamber does not impact fabric utilizationbecause of the novel design proposed in this invention as seen in FIGS.40.

[0107] An exemplary fabric layout for a two chamber passenger airbag isshown in FIG. 41.

[0108]FIG. 42 illustrates a three chamber passenger airbag in accordancewith the present invention.

[0109] The embodiment of FIG. 43 of the drawings is based on a modifiedconventional top mount passenger side airbag. Secondary front panels areadded over vent openings in the front panels to form secondary chambers.

[0110] In an alternative embodiment as illustrated in FIG. 44, a frontmount application is changed or modified for top dash mount applicationwithout any tradeoff in fabric utilization. In accordance with thisparticular embodiment of the present invention, a front mount bag ischanged to a top mount bag by precutting a slit in the fabric in themain panel near the bottom portion of the bag (FIG. 44). When a seam issewn to connect or close the slit, the fabric gathers around the seam tocreate an offset in the mount.

[0111] In accordance with the present invention, top mount bags can bemade in a similar fashion to front mount bags without a substantialtradeoff in fabric utilization.

[0112] Turning now to FIG. 44 of the drawings, there is shown a fabricweb 310, wherein ten fabric panels to be cut 312, 314, 316, 318, 320,322, 324, 326, 328, and 330 have been outlined. Also, specific fabricpieces to be removed and slits 328 330, 332 within the two largestfabric panels 312, 314 are outlined as well. The fabric web 310 in thisspecific example comprised nylon 6,6, 630 denier yarns, woven on ajacquard loom into a fabric 10 comprising 41 picks by 41 ends per inch.

[0113] In accordance with the present invention, slits, notches oropenings 306, 308 in panels 314, 312 are added to offset the mouthconfiguration instead of utilizing two separate side panels inaccordance with conventional passenger bags (FIG. 43). In accordancewith the present invention, fabric utilization is above at least

[0114] about 90%, preferably above about 95% as in the front mount bagwith more than a 50% reduction in total length of the seams, 40%reduction in fabric usage and predominated by straight seams.

[0115] The opening, slit, notch, or the like 306, 308 can be of anyshape depending on the required profile of the bag. The slit or notchcan also be positioned in a non-symmetrical fashion at the bottom orside of the panel depending on the relationship of the instrument paneldesign and the windshield design. This approach can be used for anygiven shape of the starting panel.

[0116] Secondary panels 328, 330 are attached over (or under) frontpanels 324, 326 to form secondary chambers.

[0117] The peak deceleration experienced by an object being brought torest by an airbag is an important parameter in determining airbagperformance. The peak declaration measured in g's (multiples of thestandard acceleration due to gravity) multiplied by the body weightgives the force exerted on the body to bring it to rest. Anotherimportant parameter is the amount of rebound experienced by an objectafter it is brought to rest. This parameter is a measure of energyimparted to the object by the airbag after bringing the object to restand plays a role in possible secondary injury such as whiplash. Stillanother important parameter is the energy imparted to an object when theobject is close enough for the bag to contact it while the bag is stillinflating. This parameter is important for out of position occupantssuch as a driver of short stature who must sit very close to thesteering wheel. In general one desires to have all three of theseparameters to be as low as possible.

[0118] For the examples cited, the double chamber bags of the presentinvention had substantially the same peak deceleration within ±2 g asthe conventional single chamber control bag. This is probably within therange of experimental error. For certain tether length and size of ventarea between the secondary and primary chambers, drop tests demonstratedthe rebound height of the double chamber bag to be, within experimentalerror, always less than that for the control bag and as low as 70% lessof the rebound height of the control bag. The energy imparted to thedouble chamber bag in the impact test was always less than that for thecontrol bag and as low as ⅓ of the energy imparted to the control bag.

[0119] Passenger Side Airbags

[0120] The concept is also applicable to passenger side airbags. Singlechamber passenger airbags that are currently in use do not havecontrolled excursion of the front reaction surface when it comes to theproviding occupant protection for both a 5^(th) percentile and a 95^(th)percentile occupants. De-powered airbags are not the long-term solutionbecause of the tradeoff in the protection for a 95^(th) percentileoccupants, even though they may be adequate for a 5^(th) to 50^(th)percentile occupants. Smart airbag technologies under development do notadequately address this problem, but only differentiate between singleand multi stage inflator firing scenarios. The solution to this problemcan not be completely answered by multistage inflators. The airbags needto deploy in stages with controlled excursion and inflated volumeindependent of the occupant size.

[0121] Today, this problem is tackled by providing a secondary baginside a primary bag (FIG. 16) or by providing a tether that would havea break away seam to control excursion in the punch-out phase of airbagdeployment. In addition to being a cost penalty (both material andlabor), these two approaches do not provide a complete and repeatablesolution, especially on the passenger side application where the areafor coverage is about twice compared to the driver side. None of theabove solutions adequately address the out-of-position occupant (OOPO)situation where the bag needs to get in position quicker.

[0122] A multi chamber airbag is disclosed herein for the passenger sidewith a novel approach to control bag excursion and the volume at thesame time. This approach is based on the current bag designs and can bereadily adaptable to any new designs. The current bag can be modified toact as a primary chamber and an outer layer of the fabric is sewn on thefront panel to create the secondary chamber. The excursion of the frontpanel of the primary bag is controlled by internal tether. The length ofthis tether travel controls the primary bag volume to provide protectionfor smaller occupants during the punch-out phase. Once the primarychamber inflates completely, then the secondary chamber inflates throughthe intercommunication vents positioned at the front panel of theprimary bag (FIGS. 17 and 18).

[0123] With reference to FIG. 17, gas is vented into the secondarychamber through vent opening sin the front panel.

[0124] With reference to FIG. 18, gas is vented into the secondarychamber by passing through a permeable fabric or material sewn insidethe body of the airbag (such as an uncoated fabric).

[0125] The two-chamber passenger bag of the present invention can bemade according to FIGS. 17-28.

[0126] Preferably, the vent size on the primary bag used to dissipateoccupant energy is bigger than the communicating vent between theprimary and the secondary bag or chamber. In situations where a smalleroccupant will be in contact with the deploying airbag (OOPO), the firingof the second stage of the inflator would be delayed and the secondarychamber would not inflate during the punch out phase. On the contrary,when both stages of the inflator are fired to protect a larger occupant,then the secondary bag or chamber will inflate to function as a largervolume bag. Typical stages of a multi-chamber airbag deployment areshown in FIGS. 21-26.

[0127] The secondary chamber can also employ an internal baffle or atether as shown in FIGS. 27 and 28.

[0128] These specific configurations and shapes provide the lowestoverall fabric usage as compared to the available inflation airspacevolume.

[0129] Each of these panels may be formed from a number of materialsincluding by way of example only and not limitation woven fabrics,knitted fabrics, non-woven fabrics, films, laminates, and combinationsthereof. Woven fabrics may be preferred with woven fabrics formed oftightly woven construction such as plain or panama weave constructionsbeing particularly preferred. Such woven fabrics may be formed fromyarns of polyester, polyamides such as nylon 6 and nylon-6,6 or othersuitable material as may be known to those in the skill in the art.Multifilament yarns having a relatively low denier per filament ratingof not greater than about 1-4 denier per filament may be desirable forbags requiring particular good foldability.

[0130] In application, woven fabrics formed from synthetic yarns havinglinear densities of about 40 denier to about 1200 denier are believed tobe useful in the formation of the airbag according to the presentinvention. Fabrics formed from yarns having linear densities of about315 to about 840 are believed to be particularly useful, and fabricsformed from yarns having linear densities in the range of about 400 toabout 650 are believed to be most useful.

[0131] While each of the panels may be formed of the same material, thepanels may also be formed from differing materials and or constructions,such as, without limitation, coated or uncoated fabrics. For example,the front panel of the primary chamber may be uncoated if the fabricsewn to the extension of the front panel is coated. Such fabrics mayprovide high permeability fabric having an air permeability of about 5CMF per square foot or higher, preferably less than about 3 CFM persquare foot or less when measured at a differential pressure of 0.5inches of water across the fabric. Fabrics having permeabilities ofabout 1-3 CFM per square foot may be desirable as well. Fabrics havingpermeabilities below 2 CFM and preferably below 1 CFM in the uncoatedstate may be preferred. Such fabrics which have permeabilities below 2CFM which permeability does not substantially increase by more than afactor of about 2 when the fabric is subjected to biaxial stresses inthe range of up to about 100 pounds force may be particularly preferred.Fabrics which exhibit such characteristics which are formed by means offluid jet weaving may be most preferred, although as noted previously,weaving on jacquard and/or dobby looms also permits seam productionwithout the need for any further labor-intensive sewing or weldingoperations.

[0132] In the event that a coating is utilized on one or more materialpanels, neoprene, silicone urethanes or disperse polyamides may bepreferred. Coatings such as dispersed polyamides having dry add onweights of about 0.6 ounces per square yard or less and more preferablyabout 0.4 ounces per square yard or less and most preferably about 0.3per square yard or less may be particularly preferred so as to minimizefabric weight and enhance foldability. It is, of course, to beunderstood that aside from the use of coatings, differentcharacteristics in various panels may also be achieved through the useof fabrics incorporating differing weave densities and/or finishingtreatments such as calendaring as may be known to those in the skill ofthe art.

[0133] While the airbag cushions according to the present invention havebeen illustrated and described herein, it is to be understood that suchcushions may also include additional components such as shape definingtethers, gas vents, and the like as may be known to those in the skillof the art.

[0134] Generally, an airbag module manufacturer or automobilemanufacturer will specify what dimensions and performancecharacteristics are needed for a specific model and make of car. Thus,airbag inflation airspace volume, front panel protection area(particularly for passenger-side airbag cushions), and sufficientoverall protection for a passenger are such required specifications. Incomparison with commercially available airbag cushions, the inventiveairbag cushions which meet the same specifications (and actually exceedthe overall passenger protection characteristics versus the prior artcushions) but require less fabric, less seam length for sewingoperations, and/or the like thus cost appreciably less than thosecompetitive cushions.

[0135] Clearly, the inventive bags, which may possess, the same or lessavailable inflation airspace volume and front fabric panel area as thecomparative prior art commercially available cushions (bags), requiremuch less in the way of total fabric utilization, which thus correlatesinto overall much lower effective fabric usage factors. Furthermore, asnoted above, these inventive bags (cushions) either performed as well asor outperformed their commercially available, more expensive,counterparts.

[0136] While specific embodiments of the invention have been illustratedand described, it is to be understood that the invention is not limitedthereto, since modifications may certainly be made and other embodimentsof the principals of this invention will no doubt occur to those skilledin the art. Therefore, it is contemplated by the appended claims tocover any such modifications and other embodiments as incorporate thefeatures of this invention in the true spirit and scope of the claimshereto.

What I claim is:
 1. A multiple chamber airbag cushion having at leastone material component, at least two chambers, and wherein said airbagcushion possesses an effective material usage factor of less than about0.095.
 2. The airbag cushion of claim 1, wherein said airbag cushionpossesses an effective material usage factor of less than about 0.09. 3.The airbag cushion of claim 2, wherein said airbag cushion possesses aneffective material usage factor of less than about 0.085.
 4. The airbagcushion of claim 3, wherein said airbag cushion possesses an effectivematerial usage factor of less than about 0.08.
 5. The airbag cushion ofclaim 4, wherein said airbag cushion possesses and effective materialusage factor of less than about 0.075.
 6. The airbag cushion of claim 5,wherein said airbag cushion is a two-chamber tethered airbag cushion. 7.The airbag cushion of claim 1, wherein said airbag cushion isconstructed of fabric and has a fabric usage factor of less than about0.095.
 8. A multiple chamber airbag cushion having at least one materialcomponent, and wherein said airbag cushion is formed using less than5.00 square meters of material.
 9. The airbag cushion of claim 8,wherein said airbag cushion is formed using less than 4.0 square metersof material.
 10. The airbag cushion of claim 9, wherein said airbagcushion is formed using less than 3.0 square meters of material.
 11. Theairbag cushion of claim 10, wherein said airbag cushion is formed usingless than 2.0 square meters of material.
 12. The airbag cushion of claim11, wherein said airbag cushion is formed using less than 1.0 squaremeter of material.
 13. The airbag cushion of claim 12, wherein saidairbag cushion is a two chamber tethered airbag cushion.
 14. The airbagcushion of claim 8, wherein said material is at least one of coated anduncoated fabric.
 15. In an airbag cushion filled by gas duringinflation, having at least first and second panels connected by edgeseams and forming a primary chamber, the improvement comprising asecondary chamber being formed by an additional panel attached to acentral portion of the second panel, and at least one vent hole in oneof the second panel and additional panel to provide for gas to fill thesecondary chamber after the filling of the primary chamber duringinflation.
 16. The airbag cushion as recited in claim 15, wherein thethird panel is attached over at least a central portion of the outersurface of the second panel, and at least one vent hole in the secondpanel in a position located under said third panel.
 17. The airbagcushion as recited in claim 15, further comprising tethers between saidfirst and second panels, located near the center of said second panel,and forming a concave area in said second panel, below said third panel,when the airbag cushion is inflated.
 18. The airbag cushion as recitedin claim 15, wherein at least said first and second panels are at leastone of coated and uncoated fabric.
 19. The airbag cushion as recited inclaim 15, wherein all of said panels are at least one of coated anduncoated fabric.
 20. The airbag cushion as recited in claim 17, whereinall of said panels and said tethers are at least one of coated anduncoated fabric.
 21. A multiple chamber airbag cushion comprising: afirst panel having a central gas opening and at least one vent hole, asecond panel having substantially the same dimensions as the firstpanel, having at least one vent opening spaced from the center thereof,and being attached to the first panel, along the edge thereof, a thirdpanel having dimensions less than or equal to that of the second panel,having no vent openings therein, and being attached along the edgethereof to the second panel in a position covering the at least one ventopening in said second panel, and at least one tether attached betweensaid first and second panels near the center thereof and having at leastone vent opening in the side thereof to provide for the flow of gas fromthe gas opening in said first panel into a primary chamber definedbetween said first and second panels and, a secondary chamber definedbetween said second and third panels receives gas from said primarychamber through said at least one vent opening in said second panel. 22.The multiple chamber airbag cushion as recited in claim 21, wherein saidfirst, second and third panels are at least one of circular,polygon-shaped, or combinations thereof.
 23. The multiple chamber airbagcushion as recited in claim 21, wherein said third panel has smallerdimensions than said second panel.
 24. The multiple chamber airbagcushion as recited in claim 21, wherein said second panel includes atleast two spaced vent openings.
 25. The multiple chamber airbag cushionas recited in claim 21, wherein at least one of said panels has tuckedpleats to form a three dimensional shape.
 26. The multiple chamberairbag cushion as recited in claim 21, having enhanced safetyperformance characteristics since said primary chamber fills morequickly than said secondary chamber.
 27. The multiple chamber airbagcushion as recited in claim 21, wherein a plurality of tethers form afirst chamber within said primary chamber which receives gas throughsaid gas opening in said first panel and vents to a second chamber ofsaid primary chamber.
 28. The multiple chamber airbag cushion as recitedin claim 21, wherein said at least one vent opening in said second panelis located adjacent the location of attachment of said at least onetether to said second panel.
 29. The multiple chamber airbag cushion asrecited in claim 21, wherein the length of said at least one tether isselected to form a concave area in the center of the face of said secondpanel upon inflation of the airbag cushion.
 30. The multiple chamberairbag cushion as recited in claim 21, wherein said airbag cushion isconstructed by simple sewing steps of attaching said at least one tetherto said first and second panels, attaching said third panel to saidsecond panel, and then attaching said first panel to said second panel.31. The multiple chamber airbag cushion as recited in claim 21, whereinsaid secondary chamber has a smaller volume than said primary chamber.32. The multiple chamber airbag cushion as recited in claim 21, whereinsaid airbag cushion is at least one of a driver side airbag cushion,passenger side airbag cushion, side airbag cushion, and side curtainairbag cushion.
 33. The multiple chamber airbag cushion as recited inclaim 21, wherein said third panel is made of single ply fabric.
 34. Themultiple chamber airbag cushion as recited in claim 21, wherein saidthird panel is made of a soft, low abrasion material.
 35. The multiplechamber airbag cushion as recited in claim 21, wherein said first,second and third panels are fabric, and said third panel is made of afabric which is at least one of lighter, softer and less abrasive thanthe fabric of said first and second panels.
 36. The multiple chamberairbag cushion as recited in claim 21, wherein said second panel isformed of uncoated fabric.
 37. The multiple chamber airbag cushion asrecited in claim 21, wherein said first and third panels are formed ofcoated fabric.
 38. The multiple chamber airbag cushion as recited inclaim 21, wherein the length of the tether is shorter than the tether ina single chamber tethered airbag.
 39. The multiple chamber airbagcushion as recited in claim 21, wherein the length of said at least onetether is less than about 350 mm.
 40. The multiple chamber airbagcushion as recited in claim 39, wherein the length of the tether is lessthan about 300 mm.
 41. The multiple chamber airbag cushion as recited inclaim 21, wherein the at least one tether is attached to said secondpanel by a circular stitch having a diameter of at least 3 inches. 42.The multiple chamber airbag cushion as recited in claim 41, wherein thediameter of said circular stitch is about 4 to 5 inches.
 43. Themultiple chamber airbag cushion as recited in claim 21, wherein said atleast one tether is formed of uncoated fabric.
 44. The multiple chamberairbag cushion as recited in claim 21, wherein said at least one tetherserves as a gas regulator.
 45. The multiple chamber airbag cushion asrecited in claim 21, wherein additional tethers are used to control theexcursion of at least one of the primary and secondary chambers.
 46. Themultiple chamber airbag cushion as recited in claim 21, furthercomprising a fourth panel secured to said second panel over said thirdpanel, and wherein at least one of said second and third panels includesa vent opening providing for inflation of a tertiary chamber definedbetween said fourth panel and said second and third panels.
 47. Themultiple chamber airbag cushion as recited in claim 46, wherein saidfourth panel is larger than said third panel.
 48. The multiple chamberairbag cushion as recited in claim 46, wherein said panels are attachedto one another and said tethers are attached to said panels by simplesewing.
 49. The multiple chamber airbag cushion as recited in claim 21,wherein said at least one tether includes at least two tether elementswhich are attached one to another.
 50. The multiple chamber airbag asrecited in claim 49, wherein one tether element is cut at a 45° bias tothe warp and fill and the other tether element is cut at 90°.
 51. Themultiple chamber airbag cushion as recited in claim 49, wherein saidtether elements are attached to said first and second panels by acircular stitching pattern.
 52. The multiple chamber airbag cushion asrecited in claim 21, wherein said airbag cushion includes a plurality oftethers and wherein each said tether is formed of at least two partseach joined one to another along their ends substantially midway betweensaid first and second panels.
 53. The multiple chamber airbag cushion asrecited in claim 21, wherein the secondary chamber receives and isfilled by gas that has passed through the primary chamber upon inflationof the cushion.
 54. The multiple chamber airbag cushion as recited inclaim 21, wherein said at least one tether has a width of at least 3inches.
 55. The multiple chamber airbag cushion of claim 21, wherein thesize of the at least one opening vent holes in the second panel isselected to provide for a fill rate of said secondary chamber of lessthan that of the primary chamber.
 56. The multiple chamber airbagcushion of claim 55, wherein there are at least two vent openings insaid second panel and each opening is at least ½ inch in diameter. 57.The multiple chamber airbag cushion of claim 21, wherein said at leastone vent opening in said second panel are offset from corresponding ventholes in the tether to provide a gas regulation effect of between thetwo chambers.
 58. The multiple chamber airbag cushion of claim 57,wherein the vent holes in at least one of said second panel and tetherinclude elongate slits extending therefrom to provide for enlargement ofsaid vent holes upon inflation of said cushion.
 59. The multiple chamberairbag cushion as recited in claim 21, wherein the filled volume of saidprimary chamber is greater than the filled volume of said secondarychamber.
 60. The multiple chamber airbag cushion of claim 59, whereinthe filled volume of the primary chamber is about 80 to 100 liters andthe filled volume of the secondary chamber is about 30 to 50 liters. 61.The multiple chamber airbag cushion of claim 60, wherein the airbagcushion is a passenger side airbag cushion.
 62. The multiple chamberairbag cushion of claim 59, wherein the primary chamber has a filledvolume of about 38 liters and said secondary chamber has a filled volumeof about 12 liters.
 63. The multiple chamber airbag cushion of claim 21,wherein the fill volume ratio of said secondary chamber to said primarychamber is at most 1/1.
 64. The multiple chamber airbag cushion of claim63, wherein the fill volume ratio of said secondary chamber to saidprimary chamber is at most 2/3.
 65. The multiple chamber airbag cushionof claim 63, wherein the fill volume ratio of said secondary chamber tosaid primary chamber is at most 1/3.
 66. The multiple chamber airbagcushion of claim 46, wherein the fill volume of said primary chamber isgreater than that of said secondary chamber, and said fill volume ofsaid tertiary chamber is greater than that of said secondary chamber.67. A multiple chamber airbag cushion having enhanced safetycharacteristics as compared to a conventional single chamber airbag,including at least one of reduced impact, reduced rebound, smaller size,reduced possible injury to out of position occupant, faster gas fill tothe primary chamber, slower gas fill to the secondary chamber, smallerdimension of the primary chamber, smaller dimension of the secondarychamber, a softer fabric over in the secondary chamber, a lower pressurein the secondary chamber, and combinations thereof.
 68. The multiplechamber airbag cushion as recited in claim 29, wherein each of saidtethers has an enlarged substantially elongated oval central region andwherein the respective central region of each tether is adapted to beattached to the respective first and second panels.
 69. A method ofconstructing a multiple chamber airbag cushion including at least first,second, and third body panels and at least one tether, and having atleast primary and secondary inflatable chambers, comprising the steps ofattaching at least one tether to each of said first and second panels,attaching said third panel to said second panel, attaching, said firstand second panels together, and then attaching the tethers one toanother.
 70. In a vehicle occupant restraint system, the improvementcomprising a multiple chamber airbag cushion as recited in claim
 21. 71.An airbag cushion fabric layout including respective fabric parts for atleast two multiple chamber airbag cushions and using less than 5.0square meters of fabric per bag.
 72. The airbag cushion of claim 15,wherein said first and second panels are attached to one another by ripstitches.
 73. A multiple chamber driver side airbag cushion comprising:a first panel having a central gas opening and at least one vent hole, asecond panel having substantially the same dimensions as the firstpanel, having at least one vent opening spaced from the center thereof,and being attached to the first panel, along the edge thereof, a thirdpanel having dimensions less than or equal to that of the second panel,and being attached along the edge thereof to the second panel in aposition covering the at least one vent opening in said second panel,and at least one tether attached between said first and second panelsnear the center thereof and having at least one event opening in theside thereof to provide for the flow of gas from the gas opening in saidfirst panel into a primary chamber defined between said first and secondpanels, a secondary chamber defined between said second and third panelsreceives gas from said primary chamber through said at least one ventopening in said second panel.
 74. A multiple chamber passenger sideairbag cushion comprising: at least a first panel having a central gasopening and at least one vent hole, an additional panel havingdimensions less than or equal to that of the first and being attachedalong the edge thereof to the first panel in a position covering the atleast one vent hole in said first panel, and at least one tetherattached to said first panel to provide for the flow of gas from the gasopening in said first panel into a primary chamber defined by said firstpanel, and a secondary chamber defined between said first and additionalpanels receives gas from said primary chamber through said at least onevent hole in said first panel.
 75. A multiple chamber side impact airbagcushion comprising: a first panel having a central gas opening and atleast one vent hole, a second panel having substantially the samedimensions as the first panel, having at least one vent opening spacedfrom the center thereof, and being attached to the first panel, alongthe edge thereof, a third panel having dimensions less than or equal tothat of the second panel, having no vent openings therein, and beingattached along the edge thereof to the second panel in a positioncovering the at least one vent opening in said second panel, and whereingas flows from the gas opening in said first panel into a primarychamber defined between said first and second panels, a and secondarychamber defined between said second and third panels receives gas fromsaid primary chamber through said at least one vent opening in saidsecond panel.
 76. The multiple chamber driver side airbag cushion ofclaim 73, wherein the primary chamber expands upon inflation to adistance of about 350 mm inches or less from the steering column towardthe vehicle occupant.
 77. The multiple chamber driver side airbagcushion of claim 76, wherein the secondary chamber expands uponinflation to a distance of 100 mm or less from the second panel toward avehicle occupant.
 78. The multiple chamber airbag cushion of claim 21,wherein the final venting of gas from the inflated secondary chamber isback through the primary chamber and out said at least one vent hole insaid first panel.
 79. The multiple chamber airbag cushion of claim 21,wherein said airbag cushion is adapted to be used with a two stage gasinflator.
 80. The multiple chamber airbag cushion of claim 21, whereinthe multiple chamber airbag cushion provides a softer landing andreduced rebound for the occupant as compared to a single chambertethered airbag.
 81. The multiple chamber airbag cushion of claim 21,wherein the multiple chamber airbag cushion provides a shorter maximumexcursion of the primary chamber as compared to the maximum excursion ofa single chamber tethered airbag.
 82. The multiple chamber airbagcushion of claim 21, wherein said primary chamber reaches maximumpressure much faster than a single chamber tethered airbag.
 83. Themultiple chamber airbag cushion of claim 82, wherein said primarychamber reaches maximum pressure in about 40 ms or less.
 84. Themultiple chamber airbag cushion of claim 21, wherein said secondarychamber only reaches partial inflation when the primary chamber hasreached maximum inflation.
 85. The multiple chamber airbag cushion ofclaim 21, wherein the rebound distance of a drop test of the fullyinflated multiple chamber airbag cushion is at least about 10% less thanthat of a single chamber tethered airbag.
 86. The multiple chamberairbag cushion of claim 85, wherein the rebound distance is at leastabout 20% less.
 87. The multiple chamber airbag cushion of claim 85,wherein the rebound distant is at least about 70% less.
 88. The multiplechamber airbag cushion of claim 85, wherein the rebound distance is atleast about 75% less.
 89. The multiple chamber airbag cushion of claim21, wherein the effective tether length is about 500 mm or less.
 90. Themultiple chamber airbag cushion of claim 89, wherein the effectivetether length is about 400 mm or less.
 91. The multiple chamber airbagcushion of claim 90, wherein the effective tether length is about 300 mmor less.
 92. The multiple chamber airbag cushion of claim 91, whereinthe effective tether length is about 160 mm or less.
 93. The multiplechamber airbag cushion of claim 21, wherein the rebound distance of themultiple chamber airbag cushion is at least about 10% or less than thatof a single chamber tethered airbag.
 94. The multiple chamber airbagcushion of claim 21, wherein the peak deceleration (a measure of theforce experienced by the occupant) of the multiple chamber airbagcushion is about 10% less than that of a single chamber tethered airbag.95. The multiple chamber airbag cushion of claim 21, wherein the impactforce on an object rested at a first position as measured by objectmovement of the multiple chamber airbag cushion is less than that of asingle chamber tethered airbag.
 96. The multiple chamber airbag cushionof claim 95, wherein the object movement is at least about 10% less thanthat of the single chamber tethered airbag.
 97. The multiple chamberairbag cushion of claim 95, wherein the object movement is at leastabout 20% less.
 98. The multiple chamber airbag cushion of claim 95,wherein the object movement is at least about 30% less.
 99. The multiplechamber airbag cushion of claim 95, wherein the object movement is lessthan 5 inches at a distance of 10 inches.
 100. The multiple chamberairbag cushion of claim 21, wherein the multiple chamber airbag cushionprovides enhanced protection for an out-of-position occupant.
 101. Themultiple chamber airbag cushion of claim 21, wherein the multiplechamber airbag cushion provides enhanced protection for an occupantsitting too close to the airbag during deployment.
 102. The multiplechamber airbag cushion of claim 21, wherein the volume of the secondarychamber is less than about 15 liters.
 103. The multiple chamber airbagcushion of claim 21, wherein the tether length is about 160-180 mm. 104.The multiple chamber airbag cushion of claim 21, further comprising atleast one secondary tether for tethering the third panel to the secondpanel and located within the secondary chamber.
 105. The multiplechamber airbag cushion of claim 21, further comprising a fourth ventedpanel between said second and third panels and attached to said secondpanel to form a tertiary chamber between said primary and secondarychambers and serving as a gas flow modulator.
 106. The multiple chamberpassenger side airbag cushion of claim 105, wherein said fourth panel issewn on at least one of the inside and outside surface of said secondpanel.
 107. The multiple chamber airbag cushion of claim 21, whereinsaid at least one vent hole in said first panel is larger than theeffective vent size of said vent openings in said second panel betweensaid primary and secondary chambers.
 108. The multiple chamber airbagcushion of claim 21, wherein the vehicle restraint system sense asmaller occupant will be in contact with the deploying multiple chamberairbag (OOPO) and the firing of the second stage of the inflator isdelayed, the secondary chamber will not fully inflate during the punchout phase.
 109. The multiple chamber airbag cushion of claim 21, whereinwhen the vehicle restraint system senses a larger occupant and bothstages of the inflator are fired, then the primary and secondarychambers will inflate.
 110. The airbag cushion of claim 21, wherein thesecondary chamber is divided into a respective head and chest chambersto control vicious criteria.
 111. The multiple chamber airbag cushion ofclaim 21, wherein the airbag cushion includes a tertiary chamber formedby a forth panel attached to said second panel beside the third panel.112. The multiple chamber airbag cushion of claim 111, wherein thesecondary and tertiary chambers form respective head and chest chambersto control vicious criteria.
 113. The multiple chamber airbag cushion ofclaim 111, wherein the third and fourth panels are sewn to the outsideof the second panel.
 114. The multiple chamber airbag cushion of claim111, wherein the third and fourth panels are sewn to the inside of thesecond panel.
 115. The multiple chamber airbag cushion of claim 111,wherein the first, second, and third panels are woven as a single item.116. A multiple chamber airbag cushion comprising: a first panel havinga central gas opening and at least one vent hole, a second panel havingsubstantially the same dimensions as the first panel, and being attachedto the first panel, along the edge thereof, a third panel havingdimensions less than or equal to that of the second panel, and beingattached along the edge thereof to the second panel with at least one ofthe second and third panels covering at least one vent opening in theother of said panels, a secondary chamber defined between said secondand third panels receives gas from said primary chamber through said atleast one vent opening in at least one of said second and third panels.117. A multiple chamber airbag cushion comprising: a first panel havinga central gas opening and at least one vent hole, a second panel havingsubstantially the same dimensions as the first panel, having at leastone vent opening spaced from the center thereof, and being attached tothe first panel, along the edge thereof, a third panel having dimensionsless than or equal to that of the second panel, having no vent openingstherein, and being attached along the edge thereof to the second panelin a position covering the at least one vent opening in said secondpanel, and rip stitches attached between said first and second panels,and wherein gas flows from the gas opening in said first panel into aprimary chamber defined between said first and second panels, and asecondary chamber defined between said second and third panels receivesgas from said primary chamber through said at least one vent opening insaid second panel.
 118. A multiple chamber airbag cushion comprising: afirst panel having a central gas opening and at least one vent hole, asecond panel having substantially the same dimensions as the firstpanel, and being attached to the first panel, along the edge thereof, athird panel having dimensions less than or equal to that of the secondpanel, having at least one vent opening therein, and being attachedalong the edge thereof to the second panel in a position between saidfirst and second panels, and at least one tether attached between saidfirst and third panels near the center thereof and having a plurality ofvent openings in the sides thereof to provide for the flow of gas fromthe gas opening in said first panel into a primary chamber definedbetween said first and third panels, a secondary chamber defined betweensaid second and third panels receives gas from said primary chamberthrough said at least one vent opening in said third panel.
 119. Themultiple chamber airbag cushion of claim 21, wherein the panels areattached one to another by at least one of sewing, stitching, gluing,welding, sealing, and combinations thereof.
 120. The multiple chamberairbag cushion of claim 21, wherein the tether is attached by an octagonstitch.
 121. The multiple chamber airbag cushion of claim 21, whereinthe fabric utilization is optimized by cutting two tether pieces at a45° bias to the warp and fill and the other two tether pieces at 90°.122. In a module for a vehicle restraint system, the improvementcomprising the multiple chamber airbag cushion of claim
 21. 123. Amultiple chamber passenger side airbag cushion comprising at least twobody panels, a first large front panel adapted to be attached to saidbody panels to form a primary chamber, and a second smaller front paneladapted to be attached to said first large panel to form a secondarychamber there between, said large front panel having at least one ventopening therein for gas to fill the secondary chamber during inflation.124. The multiple chamber passenger side airbag cushion of claim 123,wherein said body panels are at least one of kidney shaped andpolygonal.
 125. The multiple chamber passenger side airbag cushion ofclaim 123, further comprising an additional panel adapted to be attachedto said first large front panel and form a chamber there between.
 126. Amultiple chamber airbag cushion comprising: a first panel having acentral gas opening and at least one vent hole, a second panel havingsubstantially the same dimensions as the first panel, and being attachedto the first panel, along the edge thereof, a third panel havingdimensions less than or equal to that of the second panel, beingattached along the edge thereof to the second panel, and being made of agas permeable fabric, a secondary chamber defined between said secondand third panels receives gas from said primary chamber through said gaspermeable fabric.
 127. A multiple chamber airbag cushion comprising: afirst panel having a central gas opening and at least one vent hole, asecond panel having substantially the same dimensions as the firstpanel, and being attached to the first panel, along the edge thereof, athird panel having dimensions less than or equal to that of the secondpanel, and being attached along the edge thereof, said second panelbeing made of a gas permeable fabric a secondary chamber defined betweensaid second and third panels receives gas from said primary chamberthrough said panel.
 128. A multiple chamber airbag cushion comprising: afirst panel having a central gas opening, a second panel havingsubstantially the same dimensions as the first panel, and being attachedto the first panel, along the edge thereof, to define a primary chambertherein a third panel having dimensions less than or equal to that ofthe second panel, and being attached along the edge thereof to thesecond panel, and at least one of said first, second, and third panelsbeing made of a gas permeable fabric.
 129. The airbag cushion of claim128, wherein said first panel is made of gas permeable fabric.
 130. Theairbag cushion of claim 129, wherein at least one of said second andthird panels are made of gas permeable fabric.